Masago R, Aiba-Masago S, Talal N, Zuluaga F J, Al-Hashimi I, Moody M, Lau C A, Peck A B, Brayer J, Humphreys-Beher M G, Dang H
The University of Texas Health Science Center, San Antonio, USA.
Arthritis Rheum. 2001 Mar;44(3):693-702. doi: 10.1002/1529-0131(200103)44:3<693::AID-ANR119>3.0.CO;2-7.
Salivary gland epithelial cells in patients with Sjögren's syndrome (SS) and in NOD and NODscid mice express Fas and Fas ligand, and these cells die from apoptosis. To elucidate the intracellular molecular mechanisms responsible for this salivary gland epithelial cell apoptosis, expression of the Bcl-2 family of proteins (Bcl-2, Bcl-xL, Bax) and caspase (caspases 3 and 8) was studied in young (ages 8-10 weeks) and old (ages 17-28 weeks) NOD and NOD.scid mice.
Sections of frozen salivary gland tissue were obtained from NOD and NOD.scid mice and from the lip biopsy material of SS patients. Immunohistochemistry or Western blot analysis was performed to assess the apoptotic-associated proteins.
Levels of Bax and caspase 3 were elevated in the epithelial cells of glands from old NOD mice, but not in those from young NOD mice. In contrast, epithelial cells from both young and old NOD.scid mice exhibited strong expression of Bax and caspase 3. Western blot analysis showed that the activated form of caspase 3 was increased 2-5-fold in the glands from old NOD, old NOD.scid, and young NOD.scid mice compared with those from young NOD mice. Caspase 3 was also significantly elevated (P < 0.01) in SS patients whose focus scores were grade 3 or 4. In the SS patients' biopsy tissue and in the mouse glands, cells with fragmented DNA were positive for caspase 3.
These results demonstrate that salivary gland epithelial cells in NOD and NOD.scid mice overexpress the proapoptotic molecules Bax and caspase 3. Bax could be the gene responsible for initiation of caspase activation, epithelial cell destruction, and lymphocyte glandular localization in SS.
干燥综合征（SS）患者以及非肥胖糖尿病（NOD）和NOD严重联合免疫缺陷（NODscid）小鼠的唾液腺上皮细胞表达Fas和Fas配体，且这些细胞死于凋亡。为阐明导致这种唾液腺上皮细胞凋亡的细胞内分子机制，研究了年轻（8 - 10周龄）和年老（17 - 28周龄）的NOD和NOD.scid小鼠中Bcl - 2蛋白家族（Bcl - 2、Bcl - xL、Bax）和半胱天冬酶（半胱天冬酶3和8）的表达。
从NOD和NOD.scid小鼠以及SS患者的唇活检材料中获取冷冻唾液腺组织切片。进行免疫组织化学或蛋白质印迹分析以评估凋亡相关蛋白。
年老NOD小鼠腺体的上皮细胞中Bax和半胱天冬酶3水平升高，但年轻NOD小鼠的上皮细胞中未升高。相比之下，年轻和年老NOD.scid小鼠的上皮细胞均表现出Bax和半胱天冬酶3的强表达。蛋白质印迹分析表明，与年轻NOD小鼠相比，年老NOD、年老NOD.scid和年轻NOD.scid小鼠腺体中半胱天冬酶3的活化形式增加了2 - 5倍。在焦点评分3级或4级的SS患者中，半胱天冬酶3也显著升高（P < 0.01）。在SS患者的活检组织和小鼠腺体中，DNA片段化的细胞半胱天冬酶3呈阳性。
这些结果表明，NOD和NOD.scid小鼠的唾液腺上皮细胞过度表达促凋亡分子Bax和半胱天冬酶3。Bax可能是在SS中启动半胱天冬酶激活、上皮细胞破坏和淋巴细胞腺体定位的基因。
